Computational study of liquid and gas impingement cooling using nanoparticles

Abstract

newline Jet impingement is one of the most efficient methods in various industrial processes and appliances such as gas turbine blade cooling, metal quenching, electronics cooling, textile drying, paper drying etc. The present research work deals with electronics cooling by single phase jet impingement (using air and water) and nanofluid jet impingement (air and water as base fluid with Al2O3 nanoparticles). A numerical study has been carried out for jet impingement on a heated surface at constant heat flux. A jet is coming out of a circular nozzle and impinges on a circular heated plate. Due to symmetry of the computational domain, two-dimensional, axi-symmetric simulations for turbulent jet impingement are performed for single phase jet and two-phase nanofluid jet using SST newlinek and#61559; newlineand#8722; turbulent model. For nanofluid flow, mixture model (proposed modified version) was used. The main objective of the present study is to compare heat transfer characteristics between the single phase jet and nanofluid jet by investigating the effect of main flow parameters like Reynolds number (Re), jet to surface spacing (H/D), nanoparticle diameter (d) and volume fraction ( and#61542; ). Initial validation of single phase air jet newlinehas been done followed by nanofluid jet using water with Al2O3 nanoparticles. Different turbulent models like standard k and#61541; and#8722; , RNG k and#61541; and#8722; and SSTk and#61559; and#8722; model with enhanced wall treatment are used to check its suitability for this specific application. It has been observed that the numerical predictions by SST k and#61559; and#8722; model are in good agreement when compared with experimental findings in the prediction of heat transfer. Numerical simulations were performed for different jet to plate distance (2 / 20) HD and#61603;and#61603; newlineand nozzle exit velocity (14.6 / 36.53 / ) m m s U m s and#61603;and#61603; for both single phase jet and nanofluid jet. Different volume fraction of nanoparticles (0.5% 5% and#61542; and#61603;and#61603; ) is also taken to newlineunderstand the flow physics and thermal behavior of nanofluid jet for air and water jet. Nanoparticles are of size 10 nm, 40 nm, 70